Rotors with mistuned blades

• US 5,993,161 A
• Filed: 02/20/1998
• Issued: 11/30/1999
• Est. Priority Date: 02/21/1997
• Status: Expired due to Fees

• Current Assignee: California Technology And Technology
• Original Assignee: California Institute of Technology
• Inventors: Shapiro, Benjamin
• Primary Examiner(s): Lopez, F. Daniel
• Assistant Examiner(s): Barton, Rhonda
• Application Number:
  US09/027,352
• Time in Patent Office: 648 Days
• Field of Search: 415/119, 416/203, 416/175, 416/241 R, 416/500, 416/223, 29/889.1, 29/889.21, 29/404, 29/407.01, 364/578, 364/468.03, 364/468.04
• US Class Current: 416/203
• CPC Class Codes: B63H 1/14 Propellers pitch changing B63H3/00
• CPC Class Codes: F01D 25/04 Antivibration arrangements
• CPC Class Codes: F01D 5/10 Anti- vibration means specially adapted for radial flow machines or engines F01D5/04
• CPC Class Codes: F01D 5/16 for counteracting blade vibration
• CPC Class Codes: F01D 5/26 Antivibration means not restricted to blade form or construction or to blade-to-blade connections or to the use of particular materials
• CPC Class Codes: F03D 1/0658 Arrangements for fixing wind-engaging parts to a hub
• CPC Class Codes: F04D 29/328 with unequal distribution of blades around the hub
• CPC Class Codes: F04D 29/666 by means of rotor construction or layout, e.g. unequal distribution of blades or vanes
• CPC Class Codes: F04D 29/668 damping or preventing mechanical vibrations
• CPC Class Codes: F05B 2240/20 Rotors
• CPC Class Codes: F05B 2260/80 Diagnostics
• CPC Class Codes: F05D 2240/20 Rotors
• CPC Class Codes: F05D 2260/80 Diagnostics
• CPC Class Codes: F05D 2260/961 by mistuning rotor blades or stator vanes with irregular interblade spacing, airfoil shape
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10S 416/50 Vibration damping features
• CPC Class Codes: Y10T 29/49318 Repairing or disassembling
• CPC Class Codes: Y10T 29/49321 Assembling individual fluid flow interacting members, e.g., blades, vanes, buckets, on rotary support member
• CPC Class Codes: Y10T 29/49758 During simulated operation or operating conditions
• CPC Class Codes: Y10T 29/49764 : with testing or indicating

Abstract

A method for designing a mistuned rotor with improved stability and forced response.

Claims

1. A method of designing and constructing a rotor having mistuned blades, comprising:

selecting a system model that simulates aerodynamics of said rotor, said system model including a specified aerodynamic parameter indicative of an aerodynamic property of said rotor;

applying a selected symmetry to said system model to simplify computation complexity of said system model;

determining a correlation between said specified aerodynamic parameter and a mistuning parameter of said blades; and

arranging said blades with respect to one another in a sequence based on said correlation such that said specified aerodynamic parameter is within a specified optimal range to improve a performance of said rotor.

2. A method as in claim 1, wherein determining said correlation between said specified aerodynamic parameter and a mistuning parameter of said blades comprises:

determining eigenvalues of a linear matrix indicative of said system model;

performing an eigenvalue perturbation to determine a dependence of said specified aerodynamic parameter on said mistuning parameter when said eigenvalues are differentiable; and

using a finite difference process to determine a dependence of said specified aerodynamic parameter on said mistuning parameter when said eigenvalues are not differentiable.

3. A method as in claim 1, wherein arranging said blades is based on a solution by using a global optimization process.

4. A method as in claim 1, wherein arranging said blades is based on a solution by using a global optimization process.

5. A method as in claim 1, wherein said sequence for arranging said blades is

6. A method as in claim 1, wherein said specified aerodynamic parameter is configured and selected to indicate a stability boundary of said system model.

7. A method as in claim 1, wherein said specified aerodynamic parameter is configured and selected to indicate a forced response of said system model.

8. A method as in claim 1, wherein said selected symmetry is a rotation symmetry.

9. A rotor, comprising:

a rotor disk; and

a total of r blades formed on said rotor disk and arranged symmetrically around said rotor disk, said blades having blade properties that are different from an ideal blade,

wherein said blades are arranged in a following sequence

space="preserve" listing-type="equation">z.sub.k+1 ≧

z.sub.k ≧

z.sub.k+2 ≧

z.sub.k-1 ≧

. . . ≧

z.sub.r-1 ≧

z.sub.2 ≧

z.sub.r ≧

z.sub.1,

when r is an even number;

or

space="preserve" listing-type="equation">z.sub.k+1 ≧

z.sub.k ≧

z.sub.k+2 ≧

z.sub.k-1 ≧

. . . ≧

z.sub.2 ≧

z.sub.r-1 ≧

z.sub.1 ≧

z.sub.r,

when r is an odd number, wherein z_i indicates an amount of difference in ith blade compared to said ideal blade, and k is ##EQU18##